The present invention relates generally to an attachment device for attaching accessories to fabric, and more particularly to a method and apparatus for attaching accessories to load-bearing fabric.
Load-bearing fabrics are becoming an increasingly popular load-bearing component for a wide variety of applications, such as office seating, automotive seating, keyboard trays and other similar components. Typically, load-bearing fabrics are supported over an opening by a peripheral frame. Load-bearing fabric is generally woven or otherwise fabricated from elastomeric monofilaments (or multifilaments). The elastomeric material is often combined with a support yarn. For example, in one conventional form, a plurality of elastomeric monofilaments are interwoven with a plurality of support yarns. The elastomeric material gives the load-bearing fabric a degree of elasticity. The elasticity can be controlled by varying, among other things, the characteristics of the elastomeric materials and the support yarn. This elasticity makes load-bearing fabrics particularly well suited for use in a wide variety of load supporting applications.
In many application, it is desirable to attach accessories to the load-bearing fabric. While the peripheral frame provides a structure to which accessories can sometimes be attached near the outside edge of the fabric, components attached to the inner region of the fabric, away from the periphery, must generally be attached to the fabric itself. In seating applications, seat bolsters and lumbar supports are two of the most common accessories that require attachment to fabric. Bolsters are commonly used in seating applications to provide support for the hips and thighs of the occupant of the seat. Although available in a variety of configurations, a seat bolster often includes a foam support that is disposed along opposite sides of a seat bottom. To provide proper support to a person sitting in the seat, a conventional bolster typically extends a substantial distance inwardly from the outer edge of the seat. As a result, while the outer edge of the bolster may be attached to the peripheral frame of the seat, the inner edge of the bolster is preferably somehow attached directly to the load-bearing fabric.
One conventional method of attaching an accessory to load-bearing fabric is to simply sew the accessory to the fabric at the desired location. If the accessory is made of fabric, or some other material capable of being sewn, then the manufacturer can position the accessory on the load-bearing fabric and stitch the two fabrics together. This method can be effective at firmly attaching the accessory to the fabric, but a significant drawback is the excessive assembly time. Stitching each individual accessory to the load-bearing fabric consumes a substantial amount of time, especially in the context of an assembly line. Further, in some applications, it is difficult to form the stitching where it will not be seen in the finished product. Additionally, the stitching process may damage some of the strands of the load-bearing fabric, possibly reducing the life of the product. Alternatively, adhesives can be used to adhere the accessory to the fabric by coating the contact area of the accessory and fabric with the adhesive and pressing the two together. Due to the mesh characteristic of most load-bearing fabrics, adhesive can be difficult to apply. It can also be difficult to achieve the strength and durability of bond that is necessary to meet the needs of many accessories.
An alternative method for securing a bolster to a load-bearing fabric seat is disclosed in U.S. Pat. No. 6,283,552 to Halse et al. (“Halse”). Halse is directed a fastener that is intended to be secured to a bolster, for example, by stitching. The fastener includes a number of male prongs extending from an elongated strip. Each male prong has a pointed stem and a pair of barbs that project from opposite sides of the stem. The fastener is attached by forcing the male prongs through the fabric. Once the barbs pass through the fabric they catch on the strands of the load-bearing fabric to resist removal of the fastener. This secures the fastener, and consequently the bolster, to the fabric.
The Halse fastener provides certain advantages over other conventional attachment methods, such as the sewing and adhesive methods discussed above. These benefits arise primarily from the time it can save in attaching the accessory to the load-bearing fabric. Instead of sewing or setting the adhesive of each attached accessory, the fastener and bolster assembly can quickly be pushed through the fabric and secured. The Halse fastener, however, still faces some drawbacks. The barbs extending from the male prongs rub directly on the load-bearing fabric, such that the barbs wear on the fabric with the possibility of damaging the fabric over time. Further, it can be difficult to control the strength of the attachment with this type of fastener, which can be very important, especially in the highly standardized automotive industry. Additionally, the barb size must be carefully matched to the characteristics of the load-bearing fabric to provide optimal results.